Juniperus ashei (Ashe juniper, post cedar, mountain cedar, or blueberry juniper) is a drought-tolerant evergreen tree, native to northeastern Mexico and the south-central United States north to southern Missouri; the largest areas are in central Texas, where extensive stands occur. It grows up to 10 metres (33 ft) tall, rarely 15 metres (49 ft), and provides erosion control and year-round shade for wildlife and livestock.
|J. ashei shedding pollen: mature male on right, immature tree on left, mature green females in background|
|Natural range of Juniperus ashei|
J. sabinoides (H.B.K.) Nees sensu Sargent
The feathery foliage grows in dense sprays, bright green in color. The leaves are scale-like, 2 to 5 millimetres (0.079 to 0.197 in) long, and produced on rounded (not flattened) shoots. It is a dioecious species, with separate male and female plants. The seed cones are round, 3 to 5 millimetres (0.12 to 0.20 in) long, and soft, pulpy and berry-like, green at first, maturing purple about 8 months after pollination. They contain 1–2 seeds, which are dispersed when birds eat the cones and pass the seeds in their droppings. The male cones are 3–5 mm long, yellow, turning brown after pollen release in December to February.
The pollen causes a severe allergic reaction for some people in the winter, and people who are allergic to Ashe juniper are also often allergic to the related Juniperus virginiana. Consequently, what begins as an allergy in the winter may extend into spring since the pollination of J. virginiana follows that of J. ashei. Ashe juniper is sometimes known in the area as "mountain cedar" (although neither it nor J. virginiana are cedars), and locals usually refer to the allergy as cedar fever. Left untreated, symptoms of cedar fever may develop into a more severe infection such as pneumonia.
The wood is naturally rot resistant and provides raw material for fence posts. Posts cut from old-growth Ashe junipers have been known to last in the ground for more than 50 years. Over one hundred years ago, most old-growth Ashe junipers were cut and used not only for fence posts, but also for telegraph poles and railroad ties.
When Europeans first came to the Hill Country, they sought out the cypress, post oaks and native cedar (Ashe juniper) since they provided the best building materials. The first Spanish that came in the mid-1700s built Hill Country missions using the Ashe juniper for roof beams. As a result of poor land management, the soil turned to caliche as soil eroded following decades of clearcutting and overgrazing. One of the only plants that could handle the rocky soil was the Ashe juniper. Grasses could not establish on thin rocky soils on the more rolling to flat areas, so the junipers took over there as well.
These days Ashe Junipers are now considered a weed by many landowners. Some believe that it captures large amounts of water, denying it to other plants, thus causing them to die out and allowing the Ashe Juniper to take over, although new evidence based on better research techniques conflicts with these claims.
Ranchers also consider it to be a pest plant because overgrazing by cattle selectively removes competition when they avoid the bitter-tasting juniper seedlings. This allows for a high rate of juniper establishment and reduces ranch yields. Ashe juniper does not resprout when cut; but its cousin, the redberry juniper does resprout.
The junipers that establish on overgrazed lands are young and vigorous, dense and multi-trunked, and shallow rooted. This directly contrasts the Ashe junipers the first settlers found that were large, mostly single trunk trees with some producing logs that were 2–3' in diameter and 40' long.
Where junipers do grow bushy on thinned, eroded soils, it is difficult for remaining grasses to compete for water, especially if they are still being grazed and the soils are impoverished. The presence of these dense, shallow-rooted shrubs also means less water reaches the soil than areas with sparse, short grasses, subsurface flows and deep drainage. However, their dense canopies and thick litter do reduce overland flows compared to grazed grasses. Also, much more water is evaporated from the sparse grass areas than originally calculated. Old-growth Ashe junipers are different in that they have true trunks, use less water, are slow growing, less foliated and have very deep roots. Wilcox (Texas A&M University) and Keith Owens (Texas Ag. Ext. researcher at Uvalde) are currently studying how these deeper roots may facilitate the deep drainage of water down trunk stemflows. Dr. Owens reports that for every one inch of rain, about 6 gallons of previously undocumented water is funneled down the trunks.
- Farjon, A. (2013). "Juniperus ashei". The IUCN Red List of Threatened Species. IUCN. 2013: e.T42224A2962793. doi:10.2305/IUCN.UK.2013-1.RLTS.T42224A2962793.en. Retrieved 9 November 2017.
- United States Forest Service
- Bray, William L., 1904. Forest Resources of Texas, U.S. Department of Agriculture, Bureau of Forestry, Bulletin No. 47. Government Printing Office: Washington D.C.
- McGinty, Allan (18 March 1997). "JUNIPER ECOLOGY". unidentified. Archived from the original on 16 April 2009. Retrieved 2009-01-10.
- Owens, M.K., R.K. Lyons and C.J. Alejandro. 2006. Rainfall partitioning within semiarid juniper communities: Effects of event size and canopy cover. Hydrological Processes 20:3179–3189.
|Wikimedia Commons has media related to Juniperus ashei.|
- Image Archive of Central Texas Plants detailed photographs
- Noble Foundation Plant Image Gallery photographs
- Photograph and dimensions of Texas Champion Ashe juniper
- Evaluation of the Effects of Ashe Juniper (Cedar) Control on Water Quantity, Water Quality, and Suspended-Sediment Loads in three watersheds on the Edwards Aquifer Recharge and Catchment Area, South-Central Texas